Linear guides are used inter alia in furniture construction, in relation to domestic appliances, and in motor vehicle and aircraft construction, for example on adjustable seats, drawers or pull-out tables. Various linear guide systems are known from the state of the art. Very different demands are made, depending on the respective area of use. In the case of drawers for example this can involve ease of movement when pulling out the drawer and possibly a high load-bearing capacity. In addition such linear guides are also to have a long service life even when frequent movements of a drawer are involved and they are to retain their ease of movement over their service life.
Pull-out tables are frequently fitted to the backrests of the seats in transport means like train, bus or vehicle seats for use by the passenger seated therebehind. When the pull-out table is not in use it is generally folded up to the backrest and locked to prevent it from folding down. To use the pull-out table the locking arrangement is released and the pull-out table is pivoted into the horizontal, away from the seat backrest. Particularly where the spacings between rows of seats in the transport means are large for a higher level of comfort the pull-out tables are additionally moveable after having been folded down into the horizontal position away from the backrest of the seat in front towards the passenger seated therebehind to ensure that the pull-out table can be conveniently reached and used.
The demands in terms of displaceability of such pull-out tables in transport means are high in particular in regard to the more comfortable cabin classes. Displacement of the pull-out table should involve easy movement and should be reliable and should take place with a sense of touch which is pleasant for the user. Known displacement systems for pull-out tables in the less expensive segment use simple sliding guides in which the sides of the pull-out table are displaced in a simple guide groove with pull-out stops. In addition it is known to use linear guides for the displacement pull-out tables, which involve the use of ball-mounted telescopic guides to ensure a high level of comfort of movement, ease of movement and smooth displacement. However it is precisely the ease of movement of the ball-mounted telescopic guides that also represents a disadvantage in terms of use, in the specific application of pull-out tables in transport means. As space is constricted in the transport means, the transport means are in constant movement and forces act on the pull-out table due to braking and acceleration, the pull-out table, when it has very easily moveable ball-mounted linear guides, also correspondingly easily starts to move unintentionally so that articles thereon such as for example drinks are not stably supported thereon and can drop off. Therefore hitherto sliding guides which were more difficult to move have been preferably used in transport means as they remain more stably in their one position even under the effect of horizontally acting forces due to braking and acceleration of the transport means by virtue of the higher level of static friction of the sliding elements.
A great disadvantage of sliding guides, including those which use sliding elements between the oppositely displaceable rail elements, is their sensitivity in relation to an asymmetric loading in the direction of displacement of the pull-out table, that is to say if the pull-out table is not pushed in or pulled out with the same force and speed at both sides, but in an off-center fashion. When the table is pushed in off-center relationship that very frequently results in tilting of the sliding guides so that the table guide can then be displaced only with a very great deal of difficulty or not at all. That is referred to as the “slipstick” effect.
Further demands on linear guides for pull-out tables in transport means are inexpensive manufacture, ease of fitment and repair without a high level of complication and expenditure in terms of fitment, possibly latchability in predetermined displacement positions, at least in the pulled-out position, and possibly further intermediate positions, a pleasant feel sensation and guidance with a low level of noise. In addition particularly in aircraft the components should all be as low in weight as possible so that, in spite of their comfortable displacement behavior, the conventional steel telescopic rails are rarely used here.